This excellent biography of J. Robert Oppenheimer places the eminent physicist in the context of twentieth century America. It examines the scientific leader and statesman as he confronted the dilemmas associated with the nuclear age. The author, David Cassidy, divides Oppenheimer's life into two parts that parallel America's rise to power: the private period leading to his assuming scientific leadership in 1943 of the Manhattan Project, which produced the first nuclear weapons; and the years after World War II in which he became a prominent national figure. The book provides insights into Oppenheimer's private, professional, and political life, as well as the lives of those with whom he came in contact. Of particular interest is his dispute with Edward Teller concerning the development of the hydrogen bomb, a dispute that was responsible in large part for the denial of Oppenheimer's security clearance by the U. S. Atomic Energy Commission (AEC) in 1954. Cassidy, a historian of science and biographer of German physicist Werner Heisenberg, provides excellent insights into the life and times of this complex man. Unlike many other biographers of Oppenheimer, Cassidy assesses his role as a twentieth century theoretical physicist.